1. Field of the Invention
The present invention relates to a method and apparatus for processing leaf tobacco and, in particular, to a process and apparatus for aligning tobacco leaves to facilitate the further processing of the same such as the removal of the lamina from the objectionable stem portion of the leaf or cutting across the width of the leaves for those markets that require small segments of the stem, sometimes called "Birds Eyes", to remain in the finished product.
2. Description of the Related Art
Tobacco grown throughout the world is marketed and received at processing plants in many varying sizes and types of bulk packages, such as sheets, tersa bales, farmers bales, etc. At processing plants, these bulk packages go through preparational processing to facilitate the break down of the packages into generally loose leaf form to facilitate uniform conveyance to further processing stations.
In recent years, the efforts of the cigarette tobacco industry have been directed toward achieving a larger lamina particle size. Indeed, the larger the lamina particle size, the more cigarettes can be produced from a pound of tobacco. This is known as "filling power". Hence larger particles translate to more cigarettes produced and hence increased revenues from the same poundage of tobacco.
The addition of heat and moisture, for example, permits the break down of the packages into loose leaf form with a minimum degradation of the leaves. Indeed, tobacco pliability depends on temperature, as well as moisture. For example, tobacco leaves with 14 percent moisture by weight at ambient temperature or lower tend to be brittle and will break and shatter when handled. On the other hand, when the temperature is increased substantially, the leaves become very supple and pliable. Therefore, the packages of tobacco received at the processing plant may require heat or moisture or both. This will depend on the moisture content and pliability of the tobacco when received.
Accordingly, the bulk packages of tobacco are initially conditioned by heat and/or moisture addition to minimize degradation during the further processing such, as in bulk feeders and rotary laminators which are used to break down the package into relatively loose leaf form. The loose leaves are then conveyed to either a quality color sorting and foreign matter removal processing apparatus or directly to reconditioning rotary cylinders.
The reconditioning rotary cylinders are utilized to increase the moisture of the leaves to a range of 19 to 22 percent and the temperature to a range of 120.degree. to 150.degree. F. The leaves are then fed into a series of thresher and air classifiers to tear and separate lamina or strips from the objectionable stem portion. This step is repeated until virtually all lamina has been removed and separated from the objectional stem portion.
The horsepower requirements for driving the threshers and the fans needed for air classification make the foregoing conventional processing extremely energy intensive. A further disadvantage of this conventional processing technique is that the plural threshing stages required to remove all the lamina from the objectional stem necessarily degrades the lamina particle size. Indeed, the conventional methods of threshing and separation have progressed to the point that little further increase in particle size can be expected. It is, however, desirable to process tobacco in a manner that maximizes the particle size of the finished strip product while removing the objectionable portion of the stem.